I am with my 3.0 TDI, 167 TKM just abroad outside the EU and have a “singing” sound in a warm operating state for 2 days with more acceleration, in the engine compartment I mean to be able to perceive a slight smell of something too hot cables. A direct dependence on the engine speed does not seem to exist. As a non-specialist I would first tap on the alternator or the drive belt, sounds like a typical V-belt problem (quiet at engine start) e but not. I would be grateful for relevant information, possibly also a tip if you can start a journey home of 2000km without staying in the Pampa. THANK YOU !